[0001] The present invention relates to an anaesthetic vaporiser according to the preamble
to claim 1.
[0002] An anaesthetic is usually administered to patients who, for various reasons, are
about to undergo surgery or some examination. In inhalation anaesthesia, a gas mixture
of oxygen and nitrous oxide are usually administered along with an anaesthetic. The
anaesthetic is in liquid form and must therefore be vaporised before it reaches the
patient. Dosing and vaporisation normally take place in an anaesthetic vaporiser.
[0003] A number of different types of vaporisers are known. One way to dose and vaporise
liquid anaesthetic is to draw some of the gas mixture through the liquid, causing
it to pick up anaesthetic vapour. Another way is to draw part of the gas mixture over
the surface of the liquid anaesthetic. The surface area of this liquid can be enlarged
with the aid of wicks which draws up the liquid.
[0004] Dosing in these vaporiser types is usually based on the saturation of gas, drawn
over or through the liquid, with vaporised anaesthetic. Dosing is affected by factors
such as temperature and pressure, in addition to problems in ensuring that saturation
really does take place.
[0005] In another type of vaporiser, the liquid is first boiled or transformed into vapour
in some other way. The vapour is then dosed via valves into the gas mixture supplied
to the patient. Here, problems may occur in e.g. maintaining a constant pressure for
the anaesthetic vapour (variations in pressure affect dosing).
[0006] A third version is to inject a dosed amount of liquid into the gas flow (directly
or through a filter of some kind).
[0007] Dosing can be regulated by pressurisation of the liquid or by pumping specific quantities
of the liquid from a liquid container. Document US-A-5 509 405 discloses a vaporiser
of the last type and includes all the features of the preamble of independent claim
1.
[0008] If a pump is used, it is essential for the pump to be exact and rugged. Pressure
also plays an important role here. The pump's ability to pump the correct amount of
liquid can be affected by pressure in the liquid container which, in turn, can be
affected by the egress of liquid. Liquid held in the tubing between the liquid container
and the pump also presents a problem.
[0009] One objective of the invention is to achieve a rugged and reliable anaesthetic vaporiser
that avoids the problems associated with other known anaesthetic vaporisers, as described
above.
[0010] This objective is achieved according to the invention when the anaesthetic vaporiser
is devised as is evident from the characterising part of claim 1.
[0011] Advantageous refinements and embodiments of the anaesthetic vaporiser are evident
from the dependent claims of claim 1.
[0012] Connecting a return tube in parallel across the first regulating means, e.g. a pump,
makes it easier to control pressure downstream from the pump. A second regulating
means is arranged in the return tube and a third regulating means in the dosing tube.
The control unit can dispense anaesthetic in a safe and accurate manner by controlling
at least one of the regulating means.
[0013] In one advantageous embodiment of the anaesthetic vaporiser according to the invention,
the second regulating means consists of an additional pump, and the third regulating
means consists of a dosing restriction. Pressure before the dosing restriction can
be accurately regulated by regulating the pumps, flow through the dosing restriction
thereby achieving great accuracy. Regulating one of the pumps is sufficient if the
other pumps at a constant rate.
[0014] Alternately, or as a complement, the dosing restriction can be variable. The control
unit can then control the dosing restriction to compensate for any pressure variations
occurring when there are rapid changes in dosing.
[0015] In another advantageous embodiment of the anaesthetic vaporiser according to the
invention, the second regulating means consists of a back-flow restriction and the
third regulating means of a dosing valve. The dosing valve can be controlled by the
control unit according to the pressure, so the correct dosing is achieved. The pump
can simultaneously be controlled to maintain the pressure.
[0016] As an alternative or a complement in this embodiment, the back-flow restriction can
be variable.
[0017] The return tube's second connection point can be arranged in the outlet tube upstream
from the pump. The second connection point can alternately be arranged at the liquid
container.
[0018] The liquid container can advantageously be devised with a venting device in order
to regulate the negative pressure in the container. It should be devised to minimise
the risk of leakage of anaesthetic into atmosphere.
[0019] Additional control of dosing (and an opportunity to increase accuracy) is achieved
by arranging a flow meter in the outlet tube downstream from the first connection
point.
[0020] A pressure stabiliser can be connected to the outlet tube, downstream from the first
connection point, in order to enhance the maintenance of pressure downstream from
the pump.
[0021] Arranging an anaesthetic meter to measure the anaesthetic content of the gas mixture
increases safety and improves opportunities for refining dosing control.
[0022] Safety can also be increased by arranging a shut-off valve in the outlet tube downstream
from the second regulating means.
[0023] The anaesthetic vaporiser according to the invention is described below in further
detail, referring to the figures in which
FIG. 1 shows a first embodiment of the anaesthetic vaporiser, and
FIG. 2 shows a second embodiment of the anaesthetic vaporiser.
[0024] FIG. 1 is a schematic depiction of an anaesthetic vaporiser 2 according to a first
embodiment of the invention for dosing anaesthetic into a tube 4 in which a gas mixture
flows (according to the arrow 6). The tube 4 can be a part of a fresh gas system or
a breathing circuit (re-breathing or non re-breathing).
[0025] The anaesthetic vaporiser 2 comprises a liquid container 8 holding liquid anaesthetic
10 for dosing. The anaesthetic 10 consists primarily of one of the anaesthetics desflurane,
enflurane, halothane, isoflurane or sevoflurane.
[0026] An outlet tube 12 for the anaesthetic 10 runs from the liquid container 8. The outlet
tube 12 leads to a dosing point 14 in the tube 4. The dosing point 14 can be devised
in some suitable fashion to facilitate vaporisation of the anaesthetic 10. For example,
it can have a nozzle, preferably a whirling nozzle, arranged on the end of the outlet
tube 12.
[0027] The liquid anaesthetic 10 can alternately be carried to a filter or some other porous
structure made of a suitable material (sintered metal, mesh, porous plastic, a membrane,
activated charcoal etc.). Heat can also be applied to the dosing point 14 to facilitate
vaporisation.
[0028] A number of components are arranged in the outlet tube 12. A filter 16 is arranged
immediately downstream from the liquid container 8. The purpose of this filter 16
is simply to filter particles and dirt that could otherwise disrupt dosing, out of
the system.
[0029] A pump 18 is arranged downstream from the filter 16. The pump 18 pumps liquid anaesthetic
10 from the liquid container 8. Operation of the pump 18 in dosing is described in
more detail below.
[0030] A manometer 20, a dosing valve 22, a shut-off valve 24 and a flow meter 26 are arranged
downstream from the pump 18. The function and purpose of these components are also
described below in more detail.
[0031] A return tube 28 in parallel across the pump 18 is connected to the outlet tube 12
at a first connection point 30 and a second connection point 32. In this embodiment,
the first connection point 30 is arranged between the pump 18 and the dosing valve
22. The second connection point 32 is arranged between the filter 16 and the pump
18. A back-flow restriction 34 is arranged in the return tube 28. The back-flow restriction
34 can be fixed or variable. The figure shows the latter version. The back-flow restriction
34 can alternately be replaced with a pressure regulator.
[0032] The anaesthetic vaporiser 2 is controlled by a control unit 36. Control can be exercised
in any of the following ways (or versions thereof).
[0033] One way to control the anaesthetic vaporiser 2 to dose the desired amount of liquid
anaesthetic 10, is based on controlling the pump 18 so as to maintain a pre-set pressure
between the pump 18 and the dosing valve 22. This control can be exercised regardless
of the pressure measured by the manometer 20.
[0034] The flow-through performance of the dosing valve 22 at the prevailing pressure is
known, i.e. the amount of liquid flowing through the dosing valve 22 at the prevailing
pressure is known. When the dosing valve 22 is regulated, a specific amount of liquid
anaesthetic can therefore be dosed. The dosing valve 22 can be e.g. an ON/OFF valve
controlled with a duty cycle supplying the correct dosing for the prevailing pressure
and the set dose.
[0035] The pressure drops a little when the dosing valve 22 opens to dose a specific amount.
When a fast-acting manometer 20 is used, the pump 18 is able to respond with corresponding
swiftness in restoring pressure without affecting flow through the dosing valve 22.
[0036] Operating pressure between the pump 18 and the dosing valve 22 can be affected by
the variable back-flow restriction 34 also. Pressure changes in the system can be
performed more rapidly by changing the degree of restriction. Greater operating point
dynamics and, accordingly, greater dosing dynamics can therefore be achieved.
[0037] With the variable restriction 34, the pump 18 can be allowed to run at a constant
speed. Pressure can then be maintained by merely controlling the variable restriction
34.
[0038] An alternative is to allow pressure to drop somewhat during the dosing of liquid
anaesthetic. This can be achieved by e.g. having the pump 18 operate with a constant
pump output and using a fixed back-flow restriction 34. The measured pressure curve
then becomes saw-toothed. The drops in pressure are then proportional to the amount
dosed. The amount dosed can therefore be determined from the drops in pressure.
[0039] The amount dosed can also be checked by measuring the dosed flow with the flow meter
26. The flow meter 26 does not need to be placed next to the dosing point 14 but can
be located anywhere in the outlet tube downstream from the first connection point
30.
[0040] If the amount dosed deviates excessively from the reference amount, supply can be
stopped completely by closing the dosing valve 22 or the shut-off valve 24. Shut-off
valve 24 could therefore be placed upstream of dosing valve 22 as an alternative arrangement.
Even if the figure shows that the measurement signal from the flow meter 26 goes to
the control unit 36, this safety feature can be completely separate from the dosing
control exercised by the control unit 36.
[0041] Access to the flow signal also provides scope for more refined regulation of dosing.
The different control parameters, i.e. pressure, flow, pump output, back-flow restriction,
the dosing valve's opening or duty cycle, can all be given different emphases in order
to achieve optimal dosing. For example, a neural network could be gradually taught
to control dosing.
[0042] Irrespective of which of these methods is used, the anaesthetic vaporiser according
to the first embodiment of the invention conveys specific advantages. It is, generally
speaking, easier to dose liquids than gases since liquids are virtually non-compressible.
The two-stage system with the pump in series with the valve, in combination with back-flow
via restriction, improves control over operating conditions, such as working pressure
etc. Even if the pressure in the liquid container 8 varies (is higher or lower than
the operating pressure), this does not, in principle, affect dosing.
[0043] In those instances in which there is positive pressure in the liquid container 8,
the pump 18 can be replaced with a valve, but the back-flow restriction 34 should
then be replaced with a pump at the same time in order to ensure that back-flow can
occur.
[0044] However, negative pressure will develop in the liquid container 8 with most anaesthetics
as liquid is pumped out. Imposing a limit on this negative pressure may be appropriate.
If negative pressure becomes excessive, an increasingly powerful pump 18 will be needed
to maintain the working pressure downstream from the pump 18.
[0045] One way to limit the negative pressure is shown in FIG. 1. An air tube 38 is connected
to the liquid container 8 and leads to atmosphere. A check valve 40 opens, at a fixed
or pre-set pressure gradient between atmosphere and pressure in the liquid container
8, to admit air. Alternately, a pressure regulator or valve, controlled by the pressure
measured in the liquid container 8, can be used.
[0046] A micro-porous membrane 42 is also arranged in the air tube 38. The membrane 42 passes
air but not liquid. The membrane 42 therefore prevents liquid anaesthetic from escaping
into atmosphere.
[0047] If anaesthetic vapour does pass the membrane 42, an adsorption filter 44 is also
arranged in the air tube 38. The adsorption filter 44 can be devised to adsorb anaesthetic
vapour passing towards atmosphere and desorbs the vapour when the valve 40 opens to
the passage of a flow of air from the atmosphere. The anaesthetic vapour is then returned
to the liquid container 8. The adsorption filter 44 can suitably contain activated
charcoal, e.g. coconut shell charcoal. The order in which the membrane 42, valve 40
and filter 44 are arranged is not critical.
[0048] Additional safety in both the dosing of liquid anaesthetic and patient safety in
general can be achieved by placing an anaesthetic meter 46 downstream from the dosing
point 14.
[0049] In contrast to the flow meter 26, which measures the actual flow of liquid anaesthetic,
the anaesthetic meter 46 measures the concentration of anaesthetic in the gas mixture
flowing through the tube 4. Two faults may be present when the measured concentration
deviates from a reference value for the concentration (apart from faults in the meter(s)).
One fault could be erroneous dosing of anaesthetic. The other could be an erroneous
flow of the gas mixture in the tube 4.
[0050] Regardless of which fault is involved, the anaesthetic vaporiser 2 can react immediately
to excessive concentrations of anaesthetic by closing the shut-off valve 24. Like
the safety thinking behind the flow meter 26, this safety system can be incorporated
into the control unit 36 as a completely separate unit.
[0051] Alternately, the measurement signal from the anaesthetic meter 46 can be used for
further refining dosing of the anaesthetic. If the flow of the gas mixture does not
deviate too much from the desired flow (and reaches a flow sufficient to assure the
patient's safety), dosing can be adjusted with the aid of the measured concentration.
At the same time, an alarm should still be sounded or a warning issued to the operator
whenever any deviations occur with an impact on the system's performance and/or patient
safety.
[0052] FIG. 1 also shows a pressure stabiliser 48 connected to the outlet tube downstream
from the first connection point 30. The purpose of the pressure stabiliser 48 is to
facilitate maintenance of the working pressure. The pressure stabiliser 48 can consist
of a bellows or some other variable-volume container and be loaded with a spring,
piston or some other pressure-exerting component. Pressure loading of the bellows
should preferably be adjustable so loading can be set at the working pressure. The
volume of the pressure stabiliser 48 can be dimensioned for the volumes to be dosed.
[0053] It should be noted that only the pump 18, the dosing valve 22 and the back-flow constrictor
34 are essential to the anaesthetic vaporiser's dosing function.
[0054] A second embodiment of the anaesthetic vaporiser according to the invention is shown
in FIG. 2 and is designated 50. All the components and means that can be identical
to those in the first embodiment have been assigned the same designations.
[0055] Thus, the anaesthetic vaporiser 50 comprises a liquid container 8 holding liquid
anaesthetic 10. An outlet tube 12 connects the liquid container 8 to a dosing point
14. The liquid container 8 could be a bottle containing the liquid anaesthetic 10.
The liquid container 8 could also be a small container to which a bottle containing
liquid anaesthetic is coupled, thereby avoiding re-circulation of liquid anaesthetic
to the bottle.
[0056] A filter 16, a pump 18, a shut-off valve 24 and a flow meter 26 can be arranged in
the outlet tube 12.
[0057] A return tube 28 is arranged in parallel across the pump 18 between a first connection
point 30 and a second connection point 32. In this embodiment, the second connection
point 32 is arranged at the liquid container 8. A specific advantage here (in relation
to the first embodiment) is the complete elimination of air bubbles from the part
of the system to be filled with liquid.
[0058] A venting device, consisting of a venting tube 38, a valve 40, a membrane 42 and
a filter 44, is connected to the liquid container 8.
[0059] An anaesthetic meter 46 is connected for measuring the concentration of anaesthetic
in the gas mixture.
[0060] A control unit 36 controls the anaesthetic vaporiser's 50 dosing of liquid anaesthetic
into the gas mixture in a tube 4.
[0061] The main difference compared to the first embodiment is that an additional pump 52
is provided in the return tube 28 instead of a restriction. The second connection
point 32 opens into the liquid container 8 instead of the outlet tube 12.
[0062] The dosing valve has been replaced with a dosing restriction 54. The dosing restriction
54 can be variable.
[0063] When the dosing restriction 54 is fixed, dosing can be achieved by varying the pressure
of the liquid anaesthetic immediately upstream from the dosing restriction 54. The
flow characteristics of the dosing restriction 54 at different pressures must naturally
be known, but this is easily determined by experimentation.
[0064] When the dosing restriction 54 is variable, regulation of dosing with greater accuracy
becomes possible, even if complexity increases.
[0065] As the above shows, there are many versions of conceivable regulating methods for
the anaesthetic vaporiser according to the invention. They can also be complemented
in other ways. For example, more filters can be arrayed to ensure function. Thus,
one filter can be located immediately downstream from the first connection point 30.
This filter blocks any particles from the pump 18.
1. An anaesthetic vaporiser (2; 50) for dosing a liquid anaesthetic (10), comprising
a liquid container (8) for the liquid anaesthetic (10), an outlet tube (12) from the
liquid container (8) to a dosing point (14), a first regulating means (18) for regulating
a flow of liquid anaesthetic (10) from the liquid container (8) towards the dosing
point (14) and a control unit (36) for controlling dosing, characterised in that a return tube (28) is connected in parallel across the first regulating means (18)
at a first connection point (30), downstream from the first regulating means (18),
and a second connection point (32), upstream from the first regulating means, a second
regulating means (34; 52) is arranged in the return tube (28) and a third regulating
means (22; 54) is arranged in the outlet tube (12), downstream from the first connection
point (30), the control unit (36) controlling at least one of the regulating means
(18, 34; 52, 22; 54) in dosing the liquid anaesthetic (10).
2. The anaesthetic vaporiser according to claim 1, characterised in that the first regulating means consists of a pump (18), the second regulating means consists
of a second pump (52), the third regulating means consists of a dosing restriction
(54), and a manometer (20 is arranged between the pump (18) and the dosing restriction
(54).
3. The anaesthetic vaporiser according to claim 2, characterised in that the dosing restriction (54) is variable.
4. The anaesthetic vaporiser according to claim 1, characterised in that the first regulating means consist of a pump (18), the second regulating means consists
of a back-flow restriction (34), the third regulating means consists of a dosing valve
(22) and a manometer (20) is arranged between the pump (18) and the dosing valve (22).
5. The anaesthetic vaporiser according to claim 4, characterised in that the back-flow restriction (34) is variable.
6. The anaesthetic vaporiser according to any of the above claims, characterised in that a venting device (38, 40, 42, 44) is connected to the liquid container (8).
7. The anaesthetic vaporiser according to any of the above claims, characterised in that a flow sensor (26) is arranged in the outlet tube (12), downstream from the first
connection point (30).
8. The anaesthetic vaporiser according to any of the above claims, characterised in that a pressure stabiliser (48) is arranged for the outlet tube (12), downstream from
the first connection point (30).
9. The anaesthetic vaporiser according to any of the above claims, characterised in that an anaesthetic meter (46) is arranged downstream from the dosing point (14) for measuring
the amount of anaesthetic (10) dispensed.
10. The anaesthetic vaporiser according to any of the above claims, characterised in that a shut-off valve (24) is arranged in the outlet tube (12), downstream from the third
regulating means (22; 54).
1. Ein Narkosemittelverdunster (2; 50) zum Dosieren eines flüssigen Narkosemittels (10)
mit einem Flüssigkeitsbehälter (8) für das flüssige Narkosemittel (10), einer Auslassleitung
(12) von dem Flüssigkeitsbehälter (8) zu einem Dosierpunkt (14), einem ersten Regelmittel
(18) zum Regeln eines Flusses flüssigen Narkosemittels (10) von dem Flüssigkeitsbehälter
(8) in Richtung auf den Dosierpunkt (14) und einer Steuereinheit (36) zum Steuern
der Dosierung, dadurch gekennzeichnet, dass eine Rückführleitung (28) parallel über dem ersten Regelmittel (18) an einen ersten
Anschlusspunkt (30) stromabwärts von dem ersten Regelmittel (18) und einen zweiten
Anschlusspunkt (32) stromaufwärts von dem ersten Regelmittel (18) angeschlossen ist,
dass ein zweites Regelmittel (34; 52) in der Rückführleitung (28) und ein drittes
Regelmittel (22; 54) in der Auslassleitung (12) stromabwärts von dem ersten Anschlusspunkt
(30) angeordnet sind, wobei die Steuereinheit (36) zumindest eine der Regelmittel
(18, 34; 52, 22; 54) zum Dosieren des flüssigen Narkosemittels (10) steuert.
2. Der Narkosemittelverdunster gemäß Anspruch 1, dadurch gekennzeichnet, dass das erste Regelmittel aus einer Pumpe (18) besteht, das zweite Regelmittel aus einer
zweiten Pumpe (52) besteht, das dritte Regelmittel aus einer Dosierdrosselung (54)
besteht und ein Manometer (20) zwischen der Pumpe (18) und der Dosierdrosselung (54)
angeordnet ist.
3. Der Narkosemittelverdunster gemäß Anspruch 2, dadurch gekennzeichnet, dass die Dosierdrosselung (54) variabel ist.
4. Der Narkosemittelverdunster gemäß Anspruch 1, dadurch gekennzeichnet, dass das erste Regelmittel aus einer Pumpe (18) besteht, das zweite Regelmittel aus einer
Rückflussdrosselung (34) besteht, das dritte Regelmittel aus einem Dosierventil (22)
besteht und ein Manometer (20) zwischen der Pumpe (18) und dem Dosierventil (22) angeordnet
ist.
5. Der Narkosemittelverdunster gemäß Anspruch 4, dadurch gekennzeichnet, dass die Rückflussdrosselung (34) variabel ist.
6. Der Narkosemittelverdunster nach einem der obigen Ansprüche, dadurch gekennzeichnet, dass eine Druckausgleichsvorrichtung (38, 40, 42, 44) an den Flüssigkeitsbehälter (8)
angeschlossen ist.
7. Der Narkosemittelverdunster nach einem der obigen Ansprüche, dadurch gekennzeichnet, dass ein Flusssensor (26) in der Auslassleitung (12) stromabwärts von dem ersten Anschlusspunkt
(30) angeordnet ist.
8. Der Narkosemittelverdunster nach einem der obigen Ansprüche, dadurch gekennzeichnet, dass ein Druckstabilisator (48) für die Auslassleitung (12) stromabwärts von dem ersten
Anschlusspunkt (30) angeordnet ist.
9. Der Narkosemittelverdunster nach einem der obigen Ansprüche, dadurch gekennzeichnet, dass ein Narkosemittelmesser (46) stromabwärts von dem Dosierpunkt (14) zum Messen der
Menge abgegebenen Narkosemittels (10) angeordnet ist.
10. Der Narkosemittelverdunster nach einem der obigen Ansprüche, dadurch gekennzeichnet, dass ein Absperrventil (24) in der Auslassleitung (12) stromabwärts von dem dritten Regelmittel
(22; 54) angeordnet ist.
1. Evaporateur (2, 50) d'anesthésique pour ajouter de manière dosée un anesthésique (10)
liquide, comprenant une cuve (8) à liquide pour l'anesthésique (10) liquide, un tube
(12) de sortie allant de la cuve (8) à liquide à un point (14) d'addition dosée, des
premiers moyens (18) de régulation d'un débit d'anesthésique (10) liquide de la cuve
(8) à liquide au point (14) d'addition dosée et une unité (36) de commande de l'addition
dosée, caractérisé en ce qu'un tube (28) de retour est monté en parallèle aux premiers moyens (18) de régulation
en un premier point (30) de liaison, en aval des premiers moyens (18) de régulation,
et en un deuxième point (32) de liaison en amont des premiers moyens de régulation,
des deuxièmes moyens (34, 52) de régulation sont montés dans le tube (28) de retour
et des troisièmes moyens (22, 54) de régulation sont montés dans le tube (12) de sortie,
en aval du premier point (30) de liaison, l'unité (36) de commande commandant au moins
l'un des moyens (18, 34, 52, 22, 54) de régulation pour ajouter l'anesthésique (10)
liquide de manière dosée.
2. Evaporateur d'anesthésique suivant la revendication 1, caractérisé en ce que les premiers moyens de régulation consistent en une pompe (18), les deuxièmes moyens
de régulation consistent en une deuxième pompe (52), les troisièmes moyens de régulation
consistent en un limiteur (54) d'addition dosée et un manomètre (20) est monté entre
la pompe (18) et le limiteur (54) d'addition dosée.
3. Evaporateur d'anesthésique suivant la revendication 2, caractérisé en ce que le limiteur (54) d'addition dosée est variable.
4. Evaporateur d'anesthésique suivant la revendication 1, caractérisé en ce que les premiers moyens de régulation consistent en une pompe (18), les deuxièmes moyens
de régulation consistent en un limiteur (34) de rétro-courant, les troisièmes moyens
de régulation consistent en une vanne (22) d'addition dosée et un manomètre (20) est
monté entre la pompe (18) et la vanne (22) d'addition dosée.
5. Evaporateur d'anesthésique suivant la revendication 4, caractérisé en ce que le limiteur (34) de rétro-courant est variable.
6. Evaporateur d'anesthésique suivant l'une quelconque des revendications ci-dessus,
caractérisé en ce qu'un dispositif (38, 40, 42, 44) d'évent est relié à la cuve (8) à liquide.
7. Evaporateur d'anesthésique suivant l'une quelconque des revendications ci-dessus,
caractérisé en ce qu'un capteur (26) de débit est monté dans le tube (12) de sortie, en aval du premier
point (30) de liaison.
8. Evaporateur d'anesthésique suivant l'une quelconque des revendications ci-dessus,
caractérisé en ce qu'un stabilisateur (48) de pression est monté pour le tube (12) de sortie, en aval du
premier point (30) de liaison.
9. Evaporateur d'anesthésique suivant l'une quelconque des revendications ci-dessus,
caractérisé en ce qu'un dispositif (46) de mesure de l'anesthésique est monté en aval du point (14) d'addition
dosée afin de mesurer la quantité d'anesthésique (10) dispensée.
10. Evaporateur d'anesthésique suivant l'une quelconque des revendications ci-dessus,
caractérisé en ce qu'une vanne (24) d'arrêt est montée dans le tube (12) de sortie, en aval des troisièmes
moyens (22, 54) de régulation.